Home Forums Reloading Big Game Rifles 7mm Remington mag slow barrel

Is it possible to have a inherently slow barrel or can it be remedied with just the right powder/bullet combination?

I had been thinking about rechambering my 7 mag to a 7-300 win mag. Is it a waste of time? I don't mind the extra work for a wildcat, I just want respectable velocity in the rifle.

I get 2800 fps from 63.1 RL 22 with a 154 Hornady interlock. My 308 with a 22" barrel with 150 BT are only about 75fps behind.

I don't know what causes this but do believe it is real. I would ditch that barrel and get a good one for either cartridge or the Mashburn. And if you wanted more the 27 Nosler.

Your load would be a light one in my rifle with a long throat. I am running 65 gr. of R22 with 160s for about 3050 fps. I would try some known or factory loads to see if it is the barrel or the chronograph. I had a slow barrel and it was due to an oversized chamber, I should of re-chambered it to verify but I just swapped out the barrel instead. Also the throats vary so much in 7RM you may have some free bore. Get or borrow a bore scope to see if it is the the chamber, throat or bore. Could be an easy fix.

Tell us a bit about your rifle.
Also, tried any other loads, powders, bullet weights? How are you vairifing the velocities?

Sorry I forgot to mention the rifle. It's a 700 adl with a 24 inch barrel. I have an older Shooting Chrony brand chronograph. I have tried other loads and can't find the records for those. The 63.1 RL 22 was my most accurate load.

I have a 7 STW in a 700 Sendero, but I want a more slender sporter weight gun for lots of walking. I have not shot or tested the STW yet. I just want to get reasonable performance and accuracy.

Pour in the powder until you hit the velocity that Alliant says you should, adjusting for any differences in barrel length, etc, or until you see traditional pressure signs, whichever occurs first.

I would try some R-26. Here is Alliant's data. I have similar results with Nosler 160 gr. AB.

7mm Rem. Magnum
Hornady 154 gr SST
Federal
3.22
24
Fed 215
Reloder 26
69.5
3,127

I had a slow 7mm back several years ago. I dropped my bullet weight down to 120gr Barnes and 120 ballistic tip. It was a deer hammer and all the speed you would want.

Another vote for RL 26. Helped my 7 mag big time

I always found it easy to get 3150-3200 with 150’s and RL22 in my 7RM. Are you getting pressure signs if you go above 2800? You didn’t really say

You want top accuracy or speed? You don't all ways get both at the same time.If it really is a slow barrel I'd drop down to a 120 nbt try slot of different loads with RL-19 & 22 then burn the barrel off it shooting it a lot. 1st maybe try another chronograph and bump your powder charge after assuring the chrono is ok. Rebarreling is the most expensive option but it isn't the only option. The slow velocity your getting will still kill every deer you can intelligently take a shot at. MB

I had a Ruger M77 7mm mag a few years ago that didn't like slow burning powder. It would blow a ball of fire out of the end of the barrel the size of a basketball with H4831. It didn't matter if you put more powder the speed still wouldn't increase. I switched to IMR 4350. It stopped breathing fire like a dragon and shot 200 fps faster.

Any documented factory load speeds I should run through my rifle and chronograph to verify accuracy? What chronographs are you guys using?

My Ruger 7 Rem Mag 24" was slow until I used the old H 870 powder, and lately RL 26 with 160 to 180 gr bullets. Did a lot of experiments with different powders and mine really woke up with those 2 powders.

https://www.alliantpowder.com/reloaders/RecipeList.aspx?gtypeid=2

If you're looking for an inexpensive chrono that works much better than the Shooting Chrony, take a look at the ProChrono Digital.

Magneto speed is very easy to use and no calibration or changes with light intensity, good price too. It seems as accurate as much more expensive chronys.

R22 should be good but R26 will usually gain 50-75 fps. I also liked shooting the 120 Barnes and it was really moving along 3400+ fps.

I posted about slow barrels on the gun writer forum so hope they offer some opinions. I would also be tempted to fire lap it and see if that did anything, but if the problem is a long throat it will make it worse.

I had no pressure signs. Never really tried to push the envelope. Since joining the Campfire I have just been trying to learn as much as possible. I am a central Pa deer hunter. We hunt thick, brushy, mountain laurel woods. Most of my shots are 100 yards or closer. The only thing I ever shot with my 7 mag was a black bear in 1997.
I'm sure people will say, why do you care about 100 to 200 fps if all my typical shots are that close. Well I'm a "rifle loony" . I expect more from my 7 mag. Hopefully I will be able to elevate my knowledge and the guns velocity. Thanks

Thanks for your input.

Thanks for the input.

Thanks Bob. I guess it's not about the overall speed as it's about my expectations about a 7 mag and utilizing it to the best of its abilities with the 24" barrel. Thanks. Rob

....................It looks like you stopped at 63.1 gr RL22 because that load was very accurate and did not go any further. Before I would consider a re-chambering job, try the same RL22 and 154 gr Hornady bullet and increase your loads 1/2 grain at a time while checking for pressure signs and accuracy. If RL22 seems not to be doing trick then change your powder to what some have suggested here.

In your OP above, you did not mention whether you have tried other powders. As a reloader you should always try different powder/bullet combos for at least two reasons. The first. Which combo of bullets, powder and charge in grains gives the best accuracy?. Second. Which combos offer the best accuracy AND velocities?

You need to know or should know what your rifle is capable of. And yeah! Ya got a 7mm Rem Mag there not a 308. So see what she can really do!!

My 7 Rem Max with RL-22 and the 154 grn Hornady produces 3160 fps, with groups around 1". Bump your charge up a little at a time, as some one had suggested.

I have four 7mags and all of them will shoot well with 67.5grs of Reloader-22 with 150gr bullets and 66.0grs of Reloader-22 with 160gr bullets.The 4350 powders also work well on the faster burning powders.I like 65.0grs of IMR or Accurate 4350 with 150gr bullets and 63.0grs with 160gr bullets.A newer powder that I really like even better is Reloader-26.I'm loading 69.0grs with 150gr bullets and 67.5grs with 160gr bullets.

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I checked the 10th edn Horn manual and other than Retumbo and N-560 all there listed data loads are slow with the 154gr bullet . Even the 162 gr bullets are faster loads. I think you should set a side those bullets and pick up a current Nosler manual and 150 NBT as well 160 gr nosler bullets for the Rl-22. IMR 4350 and IMR 4831. For the 150 gr and go to testing again. HAAZROB I just about allways start my load work ups based on the Nosler data because it shows the powders that give the best velocity for acceptable pressure as well as what gave them the best accuracy. Sometimes their best accuracy loads are slow and sometimes the fastest but it tells you what their best prospects were in their testing.That's also saying with their test barrel not yours. I don't think based on the load you were using that you can say "you have a slow barrel". Bobw

Some one I think MD mentioned that he thought they used a different test barrel for the 154s that produced slower loads (in the slow/fast barrel thread), best to check several sources and maybe some factory loads as a yardstick. My 23" Shilen barrel seemed slow until I switched from H4831 to H1000 & 870 and now R26. I had a 24" Rem. and used Bob Hagel loads at about a grain less than the manly loads and that one was fast. Need to go back and see how much over max those loads were.

Maybe someone mentioned this already but a lot of Remington barrels have really long throats. Generally speaking that causes velocity to plummet. If you could stick an OAL gauge in there that might tell you your problem. You might just have to maybe seat the bullet out a little further and stick a little more powder in them cases. Obviously while watching for pressure signs etc. To be crude about it.

In my experience (which is definitely less than some other people on this forum) the throat length of a rifle is often a big culprit when it comes to a "slow" barrel. My custom barreled rifles all shoot faster but they also have way tighter chambers and show pressure signs way before most of my factory barreled rifles do.

Anyways....lots of good advice here already but check the throat length. Sorry if this is obvious.

My Remington 700 in 7RM had a huge chamber and a long throat. I commonly had to use 4-6 grains more powder to get listed velocities. I landed on R22 for the win.

That gives me some hope.

Hate to leave 100 fps on the table for that 150 yard shot.

I'm just got a "rifle loony" running in my blood. I have never shot a deer over 100 yards in the woods of Pa where I hunt.

At first some of the factory loads were at about those speeds. I sometimes can get more velocity from a Barnes bullet as they create less pressure.
Some of the Speer hot cores run slower as I think the thicker jacket and harder core along with a long bearing surface generates more pressure with out increasing velocity.

I shoot 65gr RL23 160 Accubond for 3100fps in a 26" barrel Remington 700, or 63.5gr RL23 with a 175 Partition for 2950fps. A back up load, consisting of 74gr IMR 8133 with a 160 Accubond gives me 3150fps. When I started using the chronograph, I HAD been loading 65gr H4831 with a 160, but only got 2925fps. To me, this is unacceptable, and this round should give more than that. So I tested RL 23 and IMR 8133. When I did shoot RL22, a long time ago, I loaded 65gr with a 160gr Accubond. I never chronographed that load, as I didn't have one then. Your load seems to leave some room to work if you're only loading 63gr with a 154gr bullet. I would think you should be able to load 66gr without being close to having any problems. In addition, the Hornady boat tail is not a very "grabby" bullet.

Slow barrels are a real thing. My win 70 7mm is considerably slower than the rem 700 and browning I am shooting . I found some old data from the 70s and it was noted in there as well.

I tested four 7mags one day with a load they all shot very well.It was 66.0grs of Reloader-22,Rem.Case,WLRM,160gr Accubond.This was how it went.
Ruger 1-V 24" barrel - 2890fps
Ruger 1-B 26" barrel - 3100fps
Remington 700 24" Douglas barrel - 3050fps
Remington 700 Sendero 26" barrel - 3000fps

My Remington 700 Sendero 7STW likes 77.0grs of Reloader-22 with a 160gr Accubond for 3180fps

When I owned two 7mm Remington rifles I found best accuracy at around 2,950 fps with 160s and 2,850 with 175s. I didn't bother going higher.

My current 7mm magnum is a Weatherby magnum. It has a 24" barrel, and factory 160 grain ammo listed at 3,200 fps goes 3,100 fps. The factory stuff is not accurate in my rifle.

I get excellent accuracy with 160 grain Barnes TSXs at around 2,900-3,000 fps. With 140 grain TSXs accuracy is best around 3,150 fps, with 175 grain TSXs around 2,800-2,900 fps. When I load hotter, groups suffer. I'm not getting "Weatherby" velocities, and I was upset about it. I got over it when I saw groups at 450 yards well under one M.O.A.

Best advice I can give you is ditch your chronograph! A 154gr bullet at 2800FPS with a well placed shot is going to kill whatever it meet's. Back in the early 70's it was easy. If the manual said my bullet was going 4500FPS then of course that is what it was doing. Funny thing, no one could prove it wasn't doing that! And in spite of that we still managed to kill game cleanly! Spend less time worrying about how fast your bullet is going and more time worrying about where it's going!